The number of mobile phones and other wireless devices in use continues to escalate. As each wireless device initiates and receives communications, available transmission spectrum becomes ever harder to access. Global internet protocol (IP) traffic is now measured in zettabytes, fueling higher data-rate connectivity demand for on-demand consumer access. Although some large consumer providers have had success obtaining larger spectrum allocation at considerable cost, more intelligent use of existing spectrum may go significantly further in advancing data-rates in the near term.
Carrier Aggregation (CA) increases instantaneous individual data throughput by aggregating the bandwidth of multiple available channels. Increased channel flexibility, as provided by CA, improves the probability of sufficient network bandwidth. Accordingly, increased channel availability enables higher probability of a successful network connection. The increase in the number of available channels decreases the probability of the data transmission being blocked, in some cases with more than a linear one-to-one relationship. This increased resource utilization and spectrum efficiency is commonly referred to as “trunking gain.”
Traditional Carrier Aggregation (CA) transmitter architecture approaches are shown in FIG. 1 (Prior Art). Traditional CA architecture 100 dedicates a transmitter chain for each carrier channel. This allows for channel specific amplifier and filter component optimizations. The state of the art approach is to optimize the power amplifier for operation over all target carrier channels. A switch matrix is used to multiplex the power amplifier output signal between the desired bandpass filters and antenna ports. Power amplifier performance is dependent upon the output match and multiplex configuration.
Thus, traditional implementations tend to duplicate the entire amplifier chain for each discrete band or channel. Other traditional implementations reuse amplifiers and further use transfer switches to select which transmission antenna is used. Such implementations waste energy on additional amplifier chains or waste transmit power in the transfer switch, and furthermore, outphasing artifacts are dumped to a matching resistor, which limits high power handling capabilities.